Copper-extraction process



Ore 'Failing Concentrace Roascng Furnace.

50z Reducer No1 .Low Crade Con Flotahon Elec W. E. GREENAWALT COPPEREXTRACTION PROCESS Filed April l0. 1926 H1911 Grade Con. `v

Steam HydmC ORE Oversxze Thnc-kener Classlfler Fg; Acul Water Reducer No2 C0 e1* Tamm No2 CUS IN VENT o R @MM5/Mmm# Regen cld Sol..

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s No 5 H` xcesshclcl Soluon'om Concentrates. A

Excess, Wash Waierrom Concentrates,

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Patented dan. l, i927. c Y I lll/'Il'..LIAlVI E. GREENAWALT, OF DENVER,COLORADO.

COPER-EXTRACTION PROCESS.

Applcationfiled April 10, 1926. Serial No. 101,194.

y In leaching` copper ore With an acid solu- Frequently such aregeneration of acid is de tion, such as sulphuric acid, iron is alwayssir-able for leaching purposes. dissolved With the copper. In theelectroly- It thc ferrie iron is reduced With copper sis of coppersolutions containing salts ot sulphide, as set forth in some detail inmy s iron, copper is deposited While sulphuric Patents, No. 1,310,826,May 18, 1920, No. 60 acid and fer-ric sulphate are regenerated, as 1,357,1195, Nov. 2, 1920, and No. 1,489,121,

shown by thetollowing equation: lpr. 1, 1924, copper goes into solutionwith f t e simultaneous reduction o'l' the erric iron 2 J d 1 7 ICusofl- Fcsvtlls HFGKSU) While little or no acid is regenerated, .lo 2 ef/ 2 4 shown by the equations, 65

in which m represents an indeterminate amount ot sulphuric acid and g/an indeter- FGSOSlCWSICUSOeiCUSd-QB e804 minat-e amount ot' ferriesulphate. rllhe relpez( S04)34| GUS:CL1SO4+2FGSO4 +S ative amounts ofacid and 'ferrie sulphate produced by the electrolysis Will largely de-The copper sulphide may be either the nat- V70 pend on the details otoperation. For exural sulphide, such as chalcocite, covellite, or ample,lend anodes will give a relatively chalcopyrite, a high grade coppermatte as large amount of sulphuric acid With a relaobtained fromsmelting, or a precipitate obtiycly small amount of ferrie sulphate,While tained by precipitating copper from lean u carbon anodcs Will givea relatively large and :foul solutions With a'sulphide precipi- 75amount or terric sulphate with a relatively tant such as hydrogensulphide.

small amount of sulphuric acid. rlhe application of sulphur dioxide tothe Ferrie sulphate in the electrolyte is harmleach solution, orelectrolyte, is usually adiul; it re-dissolves deposited coppersomevantageous, but it will be seen thatit the what in proportion to itspresence inthe electrolysis is conducted in such Way as to 80electrolyte. Ferrous sulphate is quite haringenerate a maximum amountoffierric iron less, and ymay be beneticial. The crucial and minimumamount of acid, and the problem oit the deposition of copper fromsoferrie iron. is reduced With copper sulphide lul'ions containing ts otiron, practically before the sulphur dioxide applied, a con- 39 resolvesitself to the control, or reduction, siderable advantage Would resultover other 85 ot the ferrie iron produced in the deposimethods` oifprocedure, for the reason that tion ot the copper. There are a number ofCopper would go into solution at 'the expense reducing agents availablefor this purpose, of the terr-ic iron and Would be deposited as but onlytivo--copper sulphide and sulphur the electrolytic metal, While thesolution dioxide-Will be discussed in connection Would be maintained ata relatively low 9*? with this process. acidity, and the low aciditywould result in The reduction ot 'ferrie iron becomes more a moreeffective reduction ot the ferrie iron dillicult as the solutionincreases in acidity. with sulphur dioxide which is not reduced Ferriesulphate is easily reuucedin neutral VWith copper sulphide. A Wide rangeot op- 4? or slightly acid solutions. While its etfective @ratingconditions can thus be maintained 95 reduction in highly acid solutionsis very by increasing or diminishing the variable di'licult. For 'thisreason the solutions factors of the process, such as the relative shouldnot contain an excessive amount ot reduction of the ferrie iron withcopper sulvcid unless u large amount of acid is dephide and sulphurdioxide, the nature o the "M sired for other purposes. anodes. and therate of circulation oi the lll@ tiulphur di i'de an etl'ective reducingelectrolyte and its temperature.

nt 'tor teiwic iron under some conditions Carbon anodes, it they can beused, would properl applied, as tor example, as set regenerate a maximumamount of ferrie iron th in in; latents No. 1,353,995, Sept. 28, and aminimum amount ot acid. .lf carbon r), and nl Lst.' Feb. 5, 1924. Itanodes are used it is desirable to have a hot 195 ic iron reduced withsulphur dioxide electrolyte and vigorous circulation or agilarge amountor acid is regenerated, as tation to facilitate depolarization, whichapssoyvn by the equation pears to Vbe essential for the preservation otcarbon anodes and the generation of large 55 llegtgtli)+S2-lQH.O:QFeSO,-l-2H2SO, quant-ities of ferrie iron in they deposition119 ofthe copper Vfrom copper solutions contain lng salts of iron. i

Ferrie sulphate is a solvent torV copper in its sulphide combinations,While sulph'uric acid is not. It might besaid that the hotter thesolution or" -ferrie sulphate the more el"- y feetive it is as a solventtor copper in its by roasting, and that a very high total extraction ofvthe copper is possible Vwith "such a roast. But, with a Ylargepercentage oit' Water soluble copper due to roasting, the amount of acidregenerated in `the deposition of the copper should be maintained low4for Athe most satisfactory operation, and

' the vexcess acid to be wasted, should be mainlll tained as loiv aspossible, unless oxidized ore isavailable for its use andneutralization, and oxidized ore is not alivays available in kthetreatment of sulphide concentrate.

When copper sulphide, either in the form ot CnS, CMS, or as a high gradematte is 'used for reduction purposes in the deposition ot copper fromleach solutions containn ing salts of iron the copper sulphide shouldvlie in an easily attackable conditionrby the ferrie iron. The "naturalsulphide can be used for 'this purpose, but in View ot the fact that thenatural sulphide isv usually very dense and almost always contaminatedwith other elel'ncntg to present the best `conditions tor effectiveattach by ferrie iron, it is preferred to first tuse the coppersulphide, partly lto slag oli some of the undesirable limpurities andpartly -to convert the copper' sulphide in a condition in Which-thecopper is 'easily attacked Vby the solution` and in lt' the naturalVcopper sulphide is ground tine it a form in which it is easily applied.

islnore effective than it is in a coarse condiw tion, but the nelyground. natural copper mineral Wool, its application, both chemicallyand physically, is vgreatly simplied. In 'View of these considerationsit is prertei'red, forthe present process, to fuse the copper sulphideand then to Subject the fused copper sulphide in a small stream to the'action ot a stream of fluidpreferably a stream of compressed air-tosubdivide the copper sulphide or convert it intothe form oi mineralWool, granules, or dust, andY then to apply the copper sulphide in thiscondition to the leach solution or electrolyte as a reducing agent forthe ferrie iron and to convert the copper ot' the copper sulphide intothe electrolytie metal.

Y VHydrogen sulphide is-an edectiveprecipitation agent tor copper tromfoul and lean copper solutions, and hydrogen sulphide can be cheaplyproduced-and,electively a plied by `generating` it in connection Witithe treatment of high grade copper concentrate.

Sulphur dioxide, under some conditions, is an etl'ectivesolvent forcopper flfrom oxidized ore; it' is also an keffective reducing agent forferrie iron, especially inlove acid solutions.v The .roasting of lowgrade sulphide copper concentrate may furnish the sulphur dioxide forthese purposes.

The process Will now be described some- What in detail, reference beingmade to the accompanying drawing Which is a tloiv sheet indiagramatic-.plan oit the process.

The ore, which may be presumed to be a sulphide containing ,some oxides,is crushed andthen passes to the rod mill Where it is ground to thedesired tineness, as determined by experience to be the best under theconditions. The linely ground ore and Water, or ore pulp, issues fromthe rod mill and flows into the classilier. The oversize is returned tothe rod mill, While the ore crushed to the desired lineness liows fromthe classitier into the thickener, Where some ot the Water otclaesitieation is removed and returned to the classifier. sludge thenHows into the agitator' where it istreated with sulphur dioxide obtainedtorni roasting' low grade copper concentrate or sulphide ore. Thesulphur dioxide will combine with much ot the undesirable impurities inthe ore,such as lime, Vand with most oft the easily soluble copper.Sonietinies this treatment will -be sunpricient and give the extractionof the oxidized copper desired. generated in other steps ot thetreatn'ient, it is desirable at times to treat the ore With theregenerated acid to `get a closer extrae# tion than is possible by usingsulphur dioxide alone. ore pulp as it .Flows into the separator No. 2.Where moet of the copper solution isseparated 'from the gangue. The`gningue is then given a slight Washing, and the Wash Vwater from theslight washing may be added tothe leach copper solution. The solublecopper remaining in the partly Washed gangue or residue is then treatedto 'precipitate vthe copper-kl Hydrogen sulphide is the pre-v 'ferredprecipita'nt; this gives the copper The thickened But as considerableacid isre-` vThis acid may be added lo the ment.

precipitate in the residue in the form of copper sulphide, which issubstantially the same form as the natural sulphldes occurring in theore, and maybe similarly treated.

The-leached ore residue is then mixed with a flotation agent andthe-sulphides are sepa-- rated from the gangue by liotation, or bygravityif eective, or by both gravity and flotation combined. The barrengangue is wasted, or eliminated from further treatment by the presentprocess.

The copper sulphide concentrate is dividcd into a 'high grade and a lowgrade concentrate, and given somewhat separate treat- In theconcentration treatment oft copper ore, either by gravity or flotationor both, a certain amount of very high grade concentrate may beseparated from the large amount ot ordinary sulphide concentrate, butthe relatively small amount of very high grade concentrate will lcontaina relatively large portion of the total copper. Usually this relativelysmallportion of high grade concentrate will be in the form ofchalcocite, with probably relatively small amounts of bornite andchalcopyrite, which will contaminate the high grade concentrate with asmall amount of iron, but not enough to seriously aect the presentprocess.

The copper in what is known as porphyry, or disseminated, deposits, islargely in the form of chalcocite, CugS, and contains, theoretically,79.8%*copper and 20.2% sulhur.

The conditions of concentration can best be illustrated by taking aspecific case in the treatment of 100 tons of' ore assaying 1.5%, orpounds of copper per ton, or containing a total of 30001pounds ofcopper. It the ratio ofy concentration is 10 into 1, the result of' theconcentration'treatment would be about as follows:

90 tons tailing 0.25% copper (5 lbs.) L150 lbs. total.

10 tons concentrate 12.75% copper (255 lbs.) 2550 lbs. total.

rlhe ten tons of concentrate may then be separated into:

1.5 tons high grade concentrate, y% per (1000 lbs.) 1500 lbs. total.

8,5 tons low grade concentrate, 6.2% per (124 lbs), 1050 lbs. total.

Or, possibly, into the following.

I 1.0 ton high. grade concentrate, perV (1200 lbs), 1200 lbs. tot-al.

9.0 tons low grade concentrate, 7.5% per lbs), 1350 lbs. total.

There should be no difficulty in making a relatively small amount ofhigh grade concentrate, if much of the copper in the ore is in the formof chalcocite. per concentrate, there would be a margin of 29.8% of thetheoretical; and for a 60% copper concentrate, there would be a marginof copcop-

cop-

For a 50% cop-- 19.0% of thetheoretical. Therk latter is pref'erred-and`will be assumed for illustration, altho it will be understood that theprocess is not particularly limited to the percentage of copper in thehigh grade concentrate but that the higher the grade of the concentratethe better the process can be operated. A tonv of 60% copper concentratewould contain, approximately, copper, 1200 pounds; sulphur, 100. pounds;impurities, l00pounds. The impurities may be assumed to be mostly iron,with itscombined sulphur, Silica, alumina, and combined oxygen.

It there is kgold or silver in the ore, the high grade concentrate willcontain kthe precious metals in about the same proportion as itcontainsthe copper from the original ore. That is to say, of the total preciousmetal content in the concentrate, 117.5% will be in the one ton of 00%copper' concentrate, and 52.5% will be in the 9.0'tons oil. low gradeconcentrate assaying 7.5% copper.

Having made the separation of the inineral from the gangue and dividedthe inineral into a relatively small amount of high grade concentrateand a relatively large amount ot low grade concentrate the method ofprocedure is as follows:

The low grade concentrate is roasted so as to convert as much aspossible of the copper into sulphate, which is soluble in water andwhich makes possible a high extraction of the copper from the roastedlow grade concentrate by water and acid leaching, and on electrolysis,supplies the necessary acid for the process.k rlhe roasted low gradeconcentrate is leached with a dilute acid solution to extract thecopper', and the resulting copper solution, containing salts of iron, isthen electrolyzed tov deposit the copper, while at the same `time acidand ferrie iron are rcgenerated. Ferrie iron in the electrolyte isharmful. It redissolves copper from the cathode approximately inproportion to its presence in the electrolyte. When the ferrie iron inthe electrolyte reaches 0.5% the deposition of the copper becomesinefficient, and when it reaches 0.7 5% to 1.0% the process practicallybecomes prohibitive. For good Work, the solution flowing into the copperdepositing tanks should be as low in ferrie iron as possible, and thesolution issuing 'tromthe copper depositing tanks should not greatlyexceed 0.25% ferrie iron. lt may advantageously be less. T he ferrieiron produced by the deposition ot the copper, may advantageously bereduced either with copper sulphide in any of its various f rms, or withsulphur dioxide, or by both. For the purpose of this process it ispreferred to reduce a portion of the ferrie iron with the concentratedcopper sulphide, or the high grade concentrate, consisting largely'ofCuZS or G1155, obtained as a precipitate or occur- Een ring naturally inthe-ore, andthen treat the solution With sulphur lio-xide, preparatoryto depositing the copper. Copper sulphide in a inely divided conditionis an eiective reducingy agent for ferrie iron, While at the same timean equivalent of copper goes into least in many cases, tor the reasonthat with.

copper sulphide no acid is regenerated in the reduction and copper isytaken into solution, and the treatment ot 4the reduced or partlyreduced solution with sulphur dioxide 'appears to be benecial in theelectrolysis in givinga better e'liiciency and a more reguline deposit.It also acts asl a reducing agent in the event that the ferrie iron isnot entirely reduced with the copper concentrate, consisting largely ofCu2@ or CuS.

1t is preferred to electrolyze the copper solution, obtained fromleaching the roasted low grade concentrate, in steps. It, for example,the rich copper solution from the roasted low grade concentrate contains4.0% copper and it is desired toV in'ipoverish it down to 2.0% beforereturning the solution to the roasted'concentrate, it is preferred to doit in t-Wo or more electrolytic units, each comprising a. CnS reducer,an SGL, reducer, and an electrolyzer or copper tank, by taking Y out1.0% ot the copper in the first electrolytic unit and 1.0% in thesecond, rather than to take out 2.0% ot the copper in one unit. lIn thefirst case halt of the copper Would be deposited from a 3.0% copper'solution and Vhalt from a 2.0% solution, While in the second case all otthe copper Would be de'- posited Jtrom approximately a 2.0% solution,and the conditions and thel results Would not be so good. l

The unroasted high grade concentrate, consisting largely of Cu2S andCnS, obtained either' as a precipitate or as the natural sulphide fromthe ore, is placed in the CnS reducers No. 1 and No. 2, in the desiredamounts` as determined by experience.

The sulphur dioxide from the roasting furnace is conducted to the SO2reducers No. 1 and No. 2. The clarified solution from the roasted lowgrade concentrate is flowed through the CUS reducer No. 1, where ferrieiron is reduced, and then through the SO2 reducer No. 1, Where thesolutiouis treated with sulphur dioxide, and then to the copper tanksNo. 1, where copper is deposited andan equivalent oit acid and torrieiron regenerated. rl`he solution, issuing from the copper tanks,containing say, from 0.10% to 0.24% i'erric iron, is returned to the CnSreducer, Where the ferrie iron is reduced to the ferrous condition Whilean equivalentV of coppergoes into solution. Thecycle is repeated andWhen the solution isreduced to about 3.0% copper from a head solution itaining about 2.0% copper and some regener-v ated acid and ferrie iron,is returned to the` roasted low grade concentrate, Whileanother portionis Wasted, or used in. leaching oxidized ore, ifoxidized ore isavailable. In this way the vcopper. solutiontrom the treat,- ment oftheroasted high grade concentrate can always be maintained at a. desiredstandard of purity or impurity.

1n reducing ferrie iron Withl copper- ,sulphide as described, .theeiliciency of the proc? ess Will'depend somewhat on the nature of thecopper sulphide and the extent of the impurities it contains. Then thecopper sulphide has been used. for. some time the impurities increaseand its eiiiciencyy asv a-reducing agent becomes less, so thatthe coppersulphide residue is removed from time to time, as determined byexperience, and the residue is roasted, either alone, but ,pref-Yerably, by simplymixing it with the low grade concentrate, and theresidual copper of the copper sulphide or high grade concentrate isrecovered with: that of the roasted low grade concentrate. f

1n roasting the high grade copper sulphide concentrate,l atter some ofthe copper has been extracted from it in` reducing ferric iron obtainedby electrolyzingcopper solutions containing iron, either alone or as amixture with the low grade concentrate, the copper can be eiiectivelyextracted from the roasted material.V It the roasted and leached residuecontains precious metals, the material is put in excellent condition forthe extraction or the precious metals, either by' cyanidation or bychlorination. The application ot' copper sulphide concentrate, asobtained either as a precipitate, as chalcocite from the ore, or asobtained by fusion, as aV reducing agent i'or ferrie iron obtained byelectrolysis of copper solutions, and the sub-` sequent roasting and:leaching ott-he copper sulphide residue, is set 'forth in` some, detailin my Patents No'. 1,340,825, 1.8, 1920; No. 1,357,495, Nov. e, 192e;No.. 1,489,121, April'l, v1924; No. 1,528,207, March 3, 1925, and in mypending` applicatiom'Serial No. 60,577-, Gotober 5, 1925. Thepresentprocess, in this respect, is a modiiicationor improvement to accomplishthe speciiic purpose set i'orth,V

It sometimes happens that most of the copper in the ore in concentratedform, is in the minerals chalcopyrite, CuFeS2, or bornite, CugFeSg, andwill occur as such in the highfgrade concentrate. Chalcopyrite andbornite are not as readily acted upon as f chalcocite, CuZS, orcovellite, CnS, by ferrie iron, and hence are not as effective either asa reducing agentfor ferrie iron, nor canthe copper be as satisfactorilyextracted from them. Under such conditions it is preferred to fuse orsmelt the high grade concentrate in an electric furnace to drive ed alarge portion of the sulphur and slag off the iron and other impurities,so that the copper of the high grade concentrate Will be convertedwholly or partly into the form of CnS or CugS. lt is desirable foreffective Work that the copper sulphide be in a finely divided conditionto get the best results of reduction of the ferrie iron and the solutionof the copper from the sulphide concentrate. The fused copper sulphidemay be crushed and ground fine in any line grinding machine adapted tothat purpose, but it is preferred to subdivide it by subjecting it to afluid stream, such as a stream of Water or a stream of compressed air orother gas, by means of Which the molten copper sulphide is subdividedinto iine particles,v as granules, shreds, or dust, and the coppersulphide in this subdivided condition is lio-ht, open and porous, whichmakes it khighly eective as a reducing agent for ferrie iron With thesimultaneous extraction of the copper.

`When the high grade sulphide concentrate is heated in an electricfurnace, in a reducing atmosphere, sulphur is volatilized as sulphurvapor. The first atom of sulphur from the chalcopyrite and bornite isdrivenoff at a relatively low temperature, and CnS is readily convertedinto Cu2S With liberation of sulphur. This sulphur vapor isconvertedinto hydrogen sulphide, and the hydrogen sulphide so formed-may be usedto precipitate the copper from lean washwaters, foul solutions, and toprecipitate the copper in soluble form in the ore pulp preparatory toflotation.

if steam or any hydrogen containing fluid is introduced into thelelectric furnace, hydrogen sulphide begins toform. Hydrogen sulphidebegins to dissociate at about 400 deg. C., and increases With the risein teinperature. rlhe temperature of the gases should not greatly exceed-500 deg. C. to get an eliicient formation of hydrogen sulphide with theleast amount of dissociation. To meet this condition, the gases escapingfrom the electric furnace are passed through the H25 rectilier, Wherethe conditions for the maximum aroduction of hydrogen sulphide canfbecontrolled and regulated. The temperature may vloe maintained tov getthe maximum formation of hydrogen sulphide from the uncomhined hydrogenand sulphur vapor, With the minimum amount of disintegration of hydrogensulphide.' In addition to the close regulation of temperature ytherectiiicr may and usually will contain material which promotes theformation of hyd ogen sulphide, such as glass or pumice, either of whichappears to act as a catalyst. C hey rectifier may consist of a tube orchamber, containing a catalyst, such as pumice, which may be heatedindirectly through the Walls of the chamber, or directly by an electriccurrent, to the desired temperature, or say, from 4&0() to 500 deg. C.The mixture of hydrogen sulphide, hydrogen, and sulphur vapor from theelectric furnace is passed through the rectifier to combine theunconibincd hydrogen with the uncombined sulphur vapor to form anequivalent of hydrogen sulphide. The gas is then used to precipitate thecopper in thekleached ore residue after leaching and preparatory toflotation. y

. ln the fusion treatment of the high grade concentrate to still furtherconcentrate it in copper, its effectiveness as a reducing agent forferrie iron is greatly increased. This implies that the copper of theyfused concentrate is more quickly dissolved, that the ferrie iron inthe electrolyte is more quiclily and effectively reduced, vand that thecopper is more economically converted into the electrolytic metal.

lf the high grade copper concentrate consists largely, sayof-chalcocite, chalcopyrite and bornite, and very likely some pyrite, a`portion of the sulphur of the sulphides is easily volatilized ordissociated, as for cxample, one atom of sulphur of the CnS or llTeSg,composing the concentrate, the CnS being converted into the Cu2S and theFefdg intothe theoretical FeS. The libe 'atedsulphur can be combinedwith hydrogen to form hydrogen sulphide, While the iron may be slaggedoft, so that the resulting product will he largely in the form of Culti.which is very highly effective as a reducing agent for ferrie iron. Theresidue of the high grade sulphide concentrate will contain the preciousmetals associated with the high grade concentrate. The residue of thehigh grade sulphide concentrate may be returned to the electric furnaceif desired, until the residue is sufficiently enriched in the preciousmetals to Warrant their separate recovery.

CugS ori CnS may be more effective tha SO., in the reduction of ferriesalts, especially if the copper sulphide isfhnely divided and thesolution is heated. lt is an advantage in this process to heat thesolution above the normal temperature naturally due to he atmosphere orthe reactions involved kin thev process, With heat supplied. from anextraneous source. The reactionbetween lao treated is relatively small,the increment of heat from an external source, necessary to keep thesolution at the desiredltemperature can be economically supplied. Y

lltl Will be seen that if carbon anodes canV be used with a high ironelectrolyte a considerable saving can be effected, and the acidity ofthe solution can be easily controlled. The oxygen released at the anodesis` largely orentirely consumed in converting ferrous iron tothe ferriecondition, and the ferrie iron is again reduced by acting 'on the coppersulphide to bring copper into solution.y The balance between the roastedconcentrate and the unroasted concentrate can be easily maintained,

l claim:v

l. A copper extraction process comprising, separating the ore into ahigh grade and a low grade copper concentrate, roasting the low gradeconcentrate, leaching the roasted low grade concentrate with a diluteacid'solution to extract `the copper, electrolyzing the resulting coppersolution containing sa'ltS of iron to deposit the copper and regenerateacid and ferrie iron, fusing the high grade concentrate and furtherconcentrating it in,y copper by lfusion, reducing the terr-ic ironformed by the electrolysis of the leach copper solution with said fusedcopper concentrate, andl again electiolyzing the solution. i

2.h A, copperv extraction process comprising, separating copper ore intoa high grade and aloW-gradecopper concentrate, roasting the lowgradeconcentrate, leaching` the roasted low gradey concentrate with adilute acid solution to extract the copper, electrolyzing the resultingcopper solution containing saltsl of iron'to deposit the copper andregenerate acid and ferrie iron, further concentratingthe copper in thehigh grade concentrate by fusion, subdividing the high grade fusedcopper concentrate and applying it to the electrolyte to reduce ferrieiron to the ferrouscondition, and then again electrolyzing the solution.

3. A copper extraction process comprising, separating copper ore into ahigh grade anda low grade copper concentrate, roasting the low gradeconcentrate, leaching the roasted low grade concentrate With a diluteacid 'solution to extract the copper, electrolyzing the resulting coppersolution containing salts of ironV to deposit the copper and regenerateacid'and ferrie iron, further concentrating the high gradepcopperconcentrate by fusion, su-bdividing the `fused concentrate by`subjecting it to the action ot a fluid, reducing the. ferrie ironfoimedby the electrolysis with said subdivided high grade ving the lowand then again electrolyziug trate enriched in copper by itusion,applying b the subdividedconcentrate to the electrolyte obtained fromleaching the roasted low grade concentrate as a reducing agent for theferrie iron produced by the electrolysis, and then again electrolyzingthe solution.

5. A copper extraction process comprising, leaching copper ore with anacid solution to extract the copper, electrolyzing the resulting coppersolution containingsalts or iron to deposit the copper and regenerateacid and ferrie iron, fusing a copper sulphide compound to enrich it incopper and then subjecting it to the action of av Huid stream tosubdivide the enriched copper sulphide compound, and applying thesubdivided copper-*sulphide compound to the electrolyte to reduce theferrie iron formed by the electrolysis` to the ferrous condition. 6. A;copper extraction process comprising, leaching copper ore With an acid4solution to extractthe copper, electrolyzing the resulting coppersolution containing salts of iron toV deposit the copper and regenerateacid and ferrie iron, reducing a, portion of the erric iron lso formedWith copper sullphicle and then another portion with sulphur dioxide,and then again electrolyzingl the solution to deposit more copper'.

7. A copper extraction process comprising, separating copper ore into ahighgradc anda low grade `copper concentrate, roastg 'ade concentrate,leaching the roastedjlow grade concentrate with an acid solution toextract the copper,electrolyzing the resulting copper solutioncontainingsalts of iron to deposit the copper and regenerateacicl`f'andieiri'c iron, treating theielectrolyte Vcontaiiiii'ig ferriciron with' the high grade copper concentrate and then with `sulphurdioxide, and then again electrolyzing the solution.

8. A copper extraction process comprising, separating copper ore into ahigh grade ing the loW vgrade concentrate, leachingV the Aand low gradecopper concentrate, roastt roastedlow grade concentrate `With an acidsolution to extract thev copper, electrolyzing the resulting coppersolution containing salts of iion to deposit the copper and regenerateacid and ferric iron, treating the electrolyte containing ferrie ironfirst with the high grade copper concentrate and then with sulphurdioxide, then again electrolyzing the solution and repeating the cycleuntil the solution is sufficiently impoverished in copper, and thenreturning the solution to the roasted low grade concentrate.'

9. A copper extraction process comprising, separating copper ore into ahigh grade and a low grade copper concentrate, roasting` the low gradeconcentrate, leaching the roasted low grade concentrate with an acidsolution to extract the copper, electrolyzing the resulting coppersolution containing salts ot iron to deposit the copper and regenerateacid and ferrie iron, treating the electrolyte containing ferrie ironwith the high grade copper concentrate and then with sulphur dioxide,then again electrolyzing the solution to deposit more copper, repeatingthe cycle until the high grade concentrate is impoverished in copper,then roasting the impoverished high grade copper concentrate andleaching it to extract the remaining copper.

10. A process of treating mixed oxide and sulphide ore of coppercomprising, grinding the ore Wet, applying sulphur dioxide to theresulting ore pulp to extract some of the copper, separating a portionof the dissolved copper froin the resulting leached residue,precipitating another portion of the dissolved copper in the leachedresidue as the sulphide, then subjecting the leached residue toflotation to extract the sulphide qui `precipitate and the naturalsulphide of the ore.4

l1. A process of treating copper ore con-V taining oxides and sulphidesf comprising, grinding the ore Wet, applying sulphur dioxide to theresulting ore pulp to extract some of' the copper, separating a portionof the dissolved copper from the leached residue, precipitating anotherportion of the copper in the leached residue, then subjecting theleached residue to flotation to extract the sulphide precipitate and thenatural sulphide of the ore as acopper concentrate, separating thecopper concentrate into a high grade and a low grade concentrate,roasting the low grade concentrate, leaching the roasted loivgradeconcentrate With an acid solution to extract the copper, electrolyzingthe resulting copper solution containing salts of iron to deposit the,copper and regenerate acid and ferrie iron, treating lthe electrolyteWiththe high grade copper concentrate Ato reduce ferrie iron to theferrous condition, and then againV electrolyzing the solution to depositmore copper.

12, A process of'treating copperv ore containing oxides and sulphidescomprising, applying sulphur dioxide to the finely ground ore pulp toextract a portion of the copper, then applying a dilute acid solution tothe ore pulp to dissolve another portion of the copper, separating alportion of the dissolved copper from the leached residue, precipitatinganother portion of the dissolved copper in the leachedresidue, thensubjecting the leached residue to flotation to extract the precipitateand the natural sulphide of the ore.

13. A copper extraction process comprising, leaching copper ore With anacid solution to extract the copper, electrolyzing the resulting coppersolution containing salts of iron to' deposit the copper and regenerateacid and ferrie iron, treating the electrolyzcd solution containingferrie iron with crmcentrated copper sulphide and then With sulphurdioxide, again electrolyzing the solution and repeating the cycle untilthe concentrated copperxsulphide becomes impoverished in copper, thenroasting the concentrated copper sulphide residue, and leaching theroasted residue to extract the copper therefrom. i

lll. A process of ti'eating'copper ore containing oxides and sulphidescomprising, leaching't-he ore with a dilute acid solution to dissolve aportion of the copper, separat- `ing a portion of the dissolved copperfrom the leach residue, precipitating another portion of" the dissolvedcopper in the leach residue as the sulphide, then subjecting the leachedresidue to flotation to extract the sulphide precipitate and the naturalsulphide of the ore, separating the resulting sulphide concentrate intoa high grade and a low grade concentrate, roasting the loW gradeconcentrate, leaching the roasted low grade concentrate with a'fdiluteacid solution to extract the copper, electrolyzing the resulting -coppersolution containing salts of iron to deposit the copper `and regenerateacid and i'ierric iron, fusing the high grade concentrate to dissociatesulphur and still i'iurtlier concentrating the high grade coucentrate,applying the fused sulphide coucentrate to the electrolyte to reduceferrie iron formed by the electrolysis to the ferrous condition,combining the dissociated sulphur from fusing the high grade concentrateWith some other element to form a precipitant for copper', and applyingthe precipitant to the leached ore to precipitate the portion oi'"thedissolved copper in the leached ore residue. i

l5. A process oiftreating"copperore comprising, concentrating the ore toseparate a sulphide concentrate from the gangue, fusing the resultingconcentrate to still further concentrateit in copper and slag offimpurities, subdividing the resulting.v fused sulphide concentrate,treatingv the subdivided concentrate with ferric iron solution todissolve copper With the simultaneous reducn et , til) tion of theferrie iron to the ferrous condition,..electr,olyz1ng the resultingcopper solution containing salts of iron to deposit. they 'copper andregenerate ,ferrie iron, returning solution containing salts ofv iron todeposit the copper and regenerate ferric iron, returning thelregenerated ferrie iron solution to the sulphide concentrate andrepeating the cycle, and controlling the solution by treating it Withthe roasted concentrate.

17. A process of treating mixed oxide and sulphide ores of coppercomprising, grinding the ore Wet, applying a gaseous reagent to theresulting oie pulp to dissolve some of the copper, separating a portionof the dissolved copperk from the resulting leached residue,precipitating another portion of the dissolved copper in the leachedresidue, then subjecting t-lie leached residue toflotation to recoverthe precipitate and the naturall sulf phide in the ore.

18. A process of, treating copper ore coniprising, concentrating the oreto obtain a high grade and a low grade sulphide concentrate, roastingthe low grade concentrate, treating the high grade sulphide concentratewith `aferric salt solution to dissolve the copper with the simultaneousVreduction of ferrie iron to ferrous iron, electrolyzing the resultingcopper solution containing salts of iron with carbon anodes to depositthe copper and regenerate ferric iron, returning the regenerated ferrieiron solution to the sulphide concentrate, controlling the acidity andiron content of the solution by treating itr with theroastedfconcentrate, andy maintaining the temperature of the solutionabove the temperature normally dueto atmospheric conditions or to heatVgenerated by chemical reactions involved in the process.

19. A process of treating copperore coinprising, concentrating the oreto obtain a sulphide concentrate, roasting a portion of the concentrate,treating another portion'of the concentrate with a kferrie salt solutionto dissolve the copper With the simultaneous reductionof ferrie iron toferrous iron, electrolyziiigthe'resulting copper solution conf.v

taining lsalts of iron to deposit the copper copper solutions to andregenerate ferrie iron, returning the regenerated ferrie iron solutionto the sulphide concentrate, regulating1 the solution by treatingit withthe roasted concentrate, and maintaining they .temperature of thesolution above the temperature normally due to at inospheric conditionsor to heat generated by chemical reaction involvedinthe process.

20. A process ofvtreating concentrated copper sulphide comprising,treating thesulphide concentrate Witha ferrie saltsolution involved inthe'process.

2l. A process of treatingcopperfore con:

taining oxides and sulphides comprising, leaching` the ore with a.dilute acid solution to dissolve a portion of the copper, separat#V inga portion ofr the dissolvedc'opper frein the leached residue,precipitating another portion of the copperl in the leached residue asthe sulphide, then subjecting the leached residue to flotation'torecoverthe sulphideV Vprecipitate and the natural'sulphide of the Yore,fseparating the resulting sulphide concentrate intoV a high gradeanda low grade concentrate, roasting thelow grade Vconcen-V trate, leachingthe roasted low f {rade'con centrate with a dilute acid `solution toer@tract the copper, fusing tlie'high lgradeeonvcentr-ate todissociate.,sulphurand still fui'-V ther concentrate the highgradeconcentrate,

sin

combiningy the dissociatedv sulphur with hydrogen to form hydrogensulphide, and

applying the hydrogen sulphideto precipitate the portion of the solubleycopper reniainingfinthe leached ore residue.

22. A process of treatingcopper oie coinprising, leaching the ore'toextract the cop per, eleetrolyzing they resulting copper solution to.deposit the copperu and` regenerate acid and ferrie iron, fusing a highgrade copper. sulphide concentrate to Vdissociate sulphur and` still4further concentrate the high grade copper concentrate, applyingthefused. copper concentrate to the electrolyteV to reduce ferrie ironformed by the elect-rely# sis to the ferrous condition, combining thedissociated sulphur vvith some-other element to form ya precipitant forcopper, and applying the copper precipitant to lean and foul Yprecipitate the QOPPQT therefrom WiLLiAM ii. ennnnavvanr.'

